Linear motor

ABSTRACT

In a linear motor according to this invention, the field permanent magnets  2  are arranged at an equal pitch around a field iron core  1  so that the poles are alternately changed. Also, an armature  3   a  on the needle side is arranged oppositely via a magnetic gap on a magnetic pole face of the field permanent magnets  2 . The armature  3   a  consists of an armature core forming the teeth and a yoke portion by punching an electromagnetic steel plate like the comb teeth, coil being wound around a plurality of teeth  4   u,    4   v  and  4   w  for this armature core to form the armature windings  5   u,    5   v  and  5   w . The teeth  6   a  without coil winding is disposed between teeth with coil winding  4   u  and  4   v  and between teeth with coil winding  4   v  and  4   w . The teeth  4   u,    4   v  and  4   w  with coil winding and the teeth  6   a  without coil winding are alternately arranged.

TECHNICAL FIELD

The present invention relates to a linear motor employed for an actuatoror conveying equipment such as a table feeder for tooling machine.

BACKGROUND ART

The linear motor comprises a field magnetic pole and an armature facingthe field magnetic pole, one of them being employed as a stator, and theother as a needle. A moving coil linear motor has the field magneticpole as stator and the armature as needle, and a moving magnet linearmotor has the field magnetic pole as needle and the armature as stator.

In patent document 1 (JP-A-2000-278931), a moving coil linear motor wasdisclosed in which to suppress a cogging thrust produced in the linearmotor, the armature is divided into a plurality of blocks, with a phasedifference provided between divided blocks of the armature, whereby theproduced cogging thrust is offset between armature blocks.

In the patent document 1, to provide the linear motor with thesuppressed cogging thrust, shorter length of armature in the thrustdirection and higher coil temperature detecting precision, the armatureis divided into a plurality of armature blocks that are arranged in thethrust direction, in which a block core of each armature block has theteeth arranged at an equal pitch, the number of teeth being an integralmultiple of the number of phases, the teeth being provided with anarmature coil with concentrated winding, and the armature coil of eacharmature block is shifted in phase by an electrical angle correspondingto an interval between armature blocks to provide a phase difference inthe cogging torque caused in each armature block, the cogging torquebeing offset to null the sum of cogging torque.

The linear motor as described in patent document 1 is constituted tosuppress the produced cogging torque, with a structure in which all theteeth of the armature has the winding, the windings of different phasesbeing adjacent within each slot, and to enhance the insulation of themotor, there is a need for providing the measures for reinforcing theinsulating material such as a coil film or interlayer paper ordecreasing the amount of coil within the slot to keep a distance betweenthe coils within the slot, as described above. A method for enhancingthe insulation of the motor by reinforcing the insulating material suchas coil film or interlayer paper had a problem that, because theinsulating material such as coil film or interlayer paper is varied inthe degree of deterioration due to constituents of the cutting water,the insulating material is difficult to select, and the material costand the number of manufacturing steps are increased.

Also, another method for enhancing the insulation of the motor bydecreasing the amount of coil within the slot to keep a distance betweenthe coils within the slot had a problem that the motor performance issacrificed, because the motor has more field ohmic loss due to thedecreased amount of coil.

Also, another method for enhancing the insulation of the motor had aproblem that the whole motor may be covered with resin to preventintrusion of the substance that deteriorates the insulation, but whenthe resin is damaged by biting chips, the cutting water possiblyintrudes through a damaged portion to deteriorate the insulation.

This invention has been achieved to solve the above-mentioned problems,and it is an object of the invention to provide a linear motor in whichthe produced cogging thrust is suppressed, and the insulation of themotor is enhanced simply.

DISCLOSURE OF THE INVENTION

The present invention provides a linear motor having the field magneticpoles having the permanent magnets arranged at an equal pitch, and anarmature facing the field magnetic poles, characterized in that anarmature core of the armature is provided with the teeth arranged at anequal pitch and an armature coil with concentrated winding around everyother teeth, wherein the number of magnetic poles with the permanentmagnets and the number of teeth in the armature core are in acombination of 5n to 6n−1 (n: natural number), and the interval of teethin the armature core is 5τ/6±τ/6 for the magnetic pole pitch τ, wherebythe productivity is increased and the phase-to-phase insulation isenhanced.

Also, when the length of motor is changed to obtain a predeterminedthrust, the armature core for every six teeth can be altered, wherebythe length of motor is easily changed in accordance with the mechanicaldimension.

Also, the invention provides a linear motor having the field magneticpoles having the permanent magnets arranged at an equal pitch, and anarmature facing the field magnetic poles, characterized in that anarmature core of the armature is provided with the teeth arranged at anequal pitch and an armature coil with concentrated winding around everyother teeth, wherein the number of magnetic poles with the permanentmagnets and the number of teeth in the armature core are in acombination of 5n to 6n+1 (n: natural number), and the interval of teethin the armature core is 5τ/6±τ/6 for the magnetic pole pitch τ, wherebyit is possible to avoid a direct impact on the windings owing to theteeth without coil winding disposed on both sides of the armature, evenwhen the motor collides at the stroke end while the linear motor isrunning, whereby the linear motor has a higher reliability.

Also, the invention provides a linear motor having the field magneticpoles having the permanent magnets arranged at an equal pitch, and anarmature facing the field magnetic poles, characterized in that anarmature core of the armature is provided with the teeth arranged at anequal pitch and an armature coil with concentrated winding around everyother teeth, wherein the number of magnetic poles with the permanentmagnets and the number of teeth in the armature core are in acombination of 7n to 6n−1 (n: natural number), and the interval of teethin the armature core is 7τ/6±τ/6 for the magnetic pole pitch τ, wherebythe productivity is increased and the phase-to-phase insulation isenhanced.

Also, when the length of motor is changed to obtain a predeterminedthrust, the armature core for every six teeth can be altered, wherebythe length of motor is easily changed in accordance with the mechanicaldimension.

Also, the invention provides a linear motor having the field magneticpoles having the permanent magnets arranged at an equal pitch, and anarmature facing the field magnetic poles, characterized in that anarmature core of the armature is provided with the teeth arranged at anequal pitch and an armature coil with concentrated winding around everyother teeth, wherein the number of magnetic poles with the permanentmagnets and the number of teeth in the armature core are in acombination of 7n to 6n+1 (n: natural number), and the interval of teethin the armature core is 7τ/6±τ/6 for the magnetic pole pitch τ, wherebyit is possible to avoid a direct impact on the windings owing to theteeth without coil winding disposed on both sides of the armature, evenwhen the motor collides at the stroke end while the linear motor isrunning, whereby the linear motor has a higher reliability.

Further, since the teeth without armature coil winding located on bothsides of the armature may be different in the shape and pitch from theother teeth, the mechanical dimension is easily adjusted.

Moreover, since of the teeth arranged at an equal pitch in the armaturecore, the teeth without armature coil winding has a smaller width thanthe teeth with armature coil winding, the thrust characteristic isimproved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing the structure of a linear motor according to anembodiment 1 of the present invention.

FIG. 2 is a view showing the structure of a linear motor according to anembodiment 2 of the invention.

FIG. 3 is a graph showing the thrust characteristics of the linearmotor.

FIG. 4 is a view showing the structure of a linear motor according to anembodiment 3 of the invention.

FIG. 5 is a view showing the structure of a linear motor according to anembodiment 4 of the invention.

FIG. 6 is a view showing the structure of a linear motor according to anembodiment 5 of the invention.

FIG. 7 is a graph showing the thrust characteristics of the linearmotor.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1

Referring to FIG. 1, the structure of a linear motor according to anembodiment 1 of this invention will be described below. FIG. 1 shows amoving coil type linear motor, in which the field permanent magnets 2are arranged at an equal pitch around a field iron core 1 on the stator(field magnetic pole) side so that the poles are alternately changed.Also, an armature 3 a on the needle side is arranged oppositely via amagnetic gap on a magnetic pole face of the field permanent magnets 2provided on the stator side. The armature 3 a consists of an armaturecore forming the teeth and a yoke portion by punching an electromagneticsteel plate like the comb teeth, coil being wound around a plurality ofteeth 4 u, 4 v and 4 w of this armature core to form the armaturewindings 5 u, 5 v and 5 w.

In FIG. 1, coil is wound around the teeth 4 u, 4 v and 4 w of thearmature 3 a to form the armature windings 5 u, 5 v and 5 w. The teeth 6a without coil winding is disposed between teeth 4 u and 4 v and betweenteeth 4 v and 4 w. The teeth 4 u, 4 v and 4 w with coil winding and theteeth 6 a without coil winding are alternately arranged.

The linear motor according to the embodiment 1 has a combination of thenumber of magnetic poles in the field magnetic poles with permanentmagnets and the number of teeth for the armature as 5n to 6n−1 (n:natural number that is a factor for deciding the number of teeth), inwhich the interval between teeth for the armature is 5τ/6±τ/6 for themagnetic pole pitch τ of the field magnetic poles, and the armaturewindings are arranged in the order of forward winding, reverse winding,and forward winding, and in the phase order of U phase, V phase and Wphase, for every other teeth from the end teeth on the left side ofFIG. 1. Also, a case with n=1 is shown in FIG. 1.

By the way, in the above description, the armature windings are arrangedin the order of forward winding, reverse winding, and forward winding,and in the phase order of U phase, V phase and W phase, for every otherteeth from the end teeth on the left side of FIG. 1. However, thearmature windings may be arranged in the order of reverse winding,forward winding and reverse winding, and in the phase order of U phase,V phase and W phase.

Also, the phase order is the U phase, V phase and W phase in the abovedescription, but may be the V phase, W phase and U phase, or W phase, Uphase and V phase, or W phase, V phase and U phase, or V phase, U phaseand W phase, or U phase, W phase and V phase.

Conventionally, the coil was wound around all the teeth. However, in thelinear motor according to the embodiment 1, the teeth 4 u, 4 v and 4 wwith coil winding and the teeth 6 a without coil winding are alternatelyarranged, and among the five teeth composing the armature three teethhave the coil winding, as shown in FIG. 1, whereby the productivity isincreased. Also, the coils forming the armature windings 5 u, 5 v and 5w are disposed via the teeth 6 a, and not adjacent with other coils,whereby the phase-to-phase insulation is increased.

Also, when the length of motor is changed to obtain a predeterminedthrust, it can be changed for every six teeth in the linear motoraccording to the embodiment 1. Thereby, the length of motor is easilychanged based on the mechanical size.

Embodiment 2

Referring to FIG. 2, the structure of a linear motor according to anembodiment 2 of this invention will be described below. In FIG. 2, theparts with reference numerals 1, 2, 4 u, 4 v, 4 w, 5 u, 5 v, 5 w and 6 aare the same as in FIG. 1, and are not described here.

Coil is wound around the teeth 4 u, 4 v and 4 w of an armature 3 b toform the armature windings 5 u, 5 v and 5 w. Also, the teeth 6 a has nocoil winding. The teeth with coil winding 4 u, 4 v and 4 w and the teeth6 a without coil winding are alternately arranged Also, the teeth 6 bwithout coil winding are formed on both sides of the armature 3 b, andhas an arbitrary shape and pitch.

The linear motor according to the embodiment 2 has a combination of thenumber of magnetic poles in the field magnetic poles with permanentmagnets and the number of teeth for the armature as 5n to 6n+1 (n:natural number that is a factor for deciding the number of teeth). Theinterval between teeth for the armature except for the teeth 6 b at bothends is 5τ/6±τ/6 for the magnetic pole pitch τ of the field magneticpoles. Also, the armature windings are arranged in the order of forwardwinding, reverse winding, and forward winding, and in the phase order ofU phase, V phase and W phase for every other teeth beginning with thesecond teeth (teeth 2 u in FIG. 2) from the end teeth 6 b on the leftside of FIG. 2. Also, a case with n=1 is shown in FIG. 2.

The armature 3 b in the linear motor according to the embodiment 2 has astructure in which the teeth 6 b without coil winding are added on bothsides of the armature 3 a in the linear motor according to theembodiment 1.

The same effects of the embodiment 1 are obtained. Since the teeth 6 bwithout coil winding are arranged on both sides of the armature 3 b, itis possible to avoid a direct impact on the windings, even when themotor collides at the stroke end while the linear motor is running,whereby the linear motor has a higher reliability.

As shown in FIG. 3, the thrust (FIG. 3A) of the linear motor having thestructure of FIG. 2 is greater than the thrust (FIG. 3B) of the linearmotor having the structure of FIG. 1.

By the way, in the above description, the case that the armaturewindings are arranged in the order of forward winding, reverse winding,and forward winding, and in the phase order of U phase, V phase and Wphase, for every other teeth beginning with the second teeth (teeth 4 uin FIG. 2) from the end teeth 6 b on the left side of FIG. 2 isreferred. However, the armature windings may be arranged in the order ofreverse winding, forward winding and reverse winding, and in the phaseorder of U phase, V phase and W phase.

Also, the case that the phase order is the U phase, V phase and W phaseis described above, but the phase order may be the V phase, W phase andU phase, or W phase, U phase and V phase, W phase, V phase and U phase,V phase, U phase and W phase, or U phase, W phase and V phase.

Embodiment 3

Referring to FIG. 4, the structure of a linear motor according to anembodiment 3 of this invention will be described below. In FIG. 4, theparts with reference numerals 1 and 2 are the same as in FIG. 1, and notdescribed here. An armature 13 a on the needle side is arrangedoppositely via a magnetic gap on a magnetic pole face of the fieldpermanent magnets 2 provided on the stator side. The armature 13 aconsists of an armature core forming the teeth and a yoke portion bypunching an electromagnetic steel plate like the comb teeth, coil beingwound around a plurality of teeth 14 u, 14 v and 14 w for this armaturecore to form the armature windings 15 u, 15 v and 15 w.

In FIG. 4, coil is wound around the teeth 14 u, 14 w and 14 v of thearmature 13 a to form the armature windings 15 u, 15 w and 15 v. Theteeth 16 a without coil winding is disposed between teeth 14 u and 14 wand between teeth 14 w and 14 v. The teeth 14 u, 14 w and 14 v with coilwinding and the teeth 16 a without coil winding are alternatelyarranged.

The linear motor according to the embodiment 3 has a combination of thenumber of magnetic poles in the field magnetic poles with permanentmagnets and the number of teeth for the armature as 7n to 6n−1 (n:natural number that is a factor for deciding the number of teeth), inwhich the interval between teeth for the armature is 7τ/6±τ/6 for themagnetic pole pitch τ of the field magnetic poles, and the armaturewindings are arranged in the order of forward winding, reverse winding,and forward winding, and in the phase order of U phase, W phase and Vphase, for every other teeth from the end teeth on the left side of FIG.4. Also, a case with n=1 is shown in FIG. 4.

By the way, in the above description, the case that the windings on theprimary side are arranged in the order of forward winding, reversewinding, and forward winding, and in the phase order of U phase, W phaseand V phase, for every other teeth from the end teeth on the left sideof FIG. 4 is referred. However, the armature windings may be arranged inthe order of reverse winding, forward winding and reverse winding, andin the phase order of U phase, W phase and V phase.

Also, in the above description, the case that the phase order is the Uphase, W phase and V phase is referred, but the phase order may be the Wphase, V phase and U phase, V phase, U phase and W phase, V phase, Wphase and U phase, W phase, U phase and V phase, or U phase, V phase andW phase.

In the linear motor according to the embodiment 3, the teeth 14 u, 4 vand 14 w with coil winding and the teeth 16 a without coil winding arealternately arranged, and among five teeth composing the armature, threeteeth have the coil winding, as shown in FIG. 4, whereby theproductivity is increased like in the embodiment 1. Also, the coilsforming the armature windings 15 u, 15 v and 15 w are disposed via theteeth 16 a, and not adjacent with other coils, whereby thephase-to-phase insulation is increased as in the embodiment 1.

Also, when the length of motor is changed to obtain a predeterminedthrust, it can be changed for every six teeth in the linear motoraccording to the embodiment 3. Thereby, the length of motor is easilychanged based on the mechanical size.

Embodiment 4

Referring to FIG. 5, the structure of a linear motor according to anembodiment 4 of this invention will be described below. In FIG. 5, theparts with reference numerals 1, 2, 14 u, 14 v, 14 w, 15 u, 15 v, 15 wand 16 a are the same as in FIG. 4, and not described here.

Coil is wound around the teeth 14 u, 14 v and 14 w of the armature 13 bto form the armature windings 15 u, 15 v and 15 w. Also, the teeth 16 ahave no coil winding. The teeth 14 u, 14 v and 14 w with coil windingand the teeth 16 a without coil winding are alternately arranged. Amongthe teeth without coil winding, the teeth 16 b are the ones provided atthe both sides of the armature 13 b, and have any shape and pitch.

The linear motor according to the embodiment 4 has a combination of thenumber of magnetic poles in the field magnetic poles with permanentmagnets and the number of teeth for the armature are 7n to 6n+1 (n:natural number that is a factor for deciding the number of teeth), inwhich the interval between teeth for the armature except for the teeth16 b on both sides is 7τ/6±τ/6 for the magnetic pole pitch τ of thefield magnetic poles, and the armature windings are arranged in theorder of forward winding, reverse winding, and forward winding, and inthe phase order of U phase, W phase and V phase, for every other teethbeginning with the second teeth (teeth 14 u in FIG. 5) from the endteeth 16 b on the left side of FIG. 5. Also, a case with n=1 is shown inFIG. 5.

The armature 13 b in the linear motor according to the embodiment 4 hasa structure in which the teeth 16 b without coil winding are added onboth sides of the armature 13 a in the linear motor according to theembodiment 3.

The same effects as the embodiment 3 are obtained. Since the teeth 16 bwithout coil winding are arranged on both sides of the armature 13 b, itis possible to avoid a direct impact on the windings, even when themotor collides at the stroke end while the linear motor is running,whereby the linear motor has a higher reliability.

By the way, in the above description, the case the armature windings arearranged in the order of forward winding, reverse winding, and forwardwinding, and in the phase order of U phase, W phase and V phase, forevery other teeth beginning with the second teeth (teeth 14 u in FIG. 5)from the end teeth 16 b on the left side of FIG. 5 is referred. However,the armature windings may be arranged in the order of reverse winding,forward winding and reverse winding, and in the phase order of U phase,W phase and V phase.

Also, the case that the phase order is the U phase, W phase and V phaseis referred in the above description, but the phase order may be the Wphase, V phase and U phase, V phase, U phase and W phase, or V phase, Wphase and U phase, W phase, U phase and V phase, or U phase, V phase andW phase.

Embodiment 5

Referring to FIG. 6, the structure of a linear motor according to anembodiment 5 of this invention will be described below. In FIG. 6, theparts with reference numerals 1 and 2 are the same as in FIG. 1, and notdescribed here. An armature 23 a on the needle side is arrangedoppositely via a magnetic gap on a magnetic pole face of the fieldpermanent magnets 2 provided on the stator side. The armature 23 aconsists of an armature core forming the teeth and a yoke portion bypunching an electromagnetic steel plate like the comb teeth, coil beingwound around a plurality of teeth 24 u, 24 v and 24 w for this armaturecore to form the armature windings 25 u, 25 v and 25 w.

In FIG. 6, coil is wound around the teeth 24 u, 24 v and 24 w of thearmature 23 a to form the armature windings 25 u, 25 v and 25 w. Theteeth 26 a without coil winding is disposed between teeth 24 u and 24 vand between teeth 24 v and 24 w. The teeth 24 u, 24 v and 24 w with coilwinding and the teeth 26 a without coil winding are alternatelyarranged.

Assuming that the maximum value of magnetic flux generated by electriccurrent is φmax, and the angular frequency of current is ω, the magneticflux φ1 interlinking the teeth (6 a, 16 a or 26 a) without coil windingis approximated by the expression (1) (t: time).φ1≅φmax·sin(ωt)+φmax·sin(ωt+(⅓)·π)  (1)

From the expression (1), the maximum value |φ1 max| of magnetic flux φ1takes places when ωt=(⅓)·π+nπ and |φ1max|=√3×φmax.

Also, the magnetic flux φ2 interlinking the teeth (4 u, 4 v, 4 w, 14 u,14 v, 14 w or 24 u, 24 v, 24 w) with coil winding is approximated by theexpression (2).φ2≅φmax·sin(ωt)+φmax·sin(ωt)  (2)

From the expression (2), the maximum value |φ2max| of magnetic flux φ2takes places when ωt=(½)·π+nπ and |φ2max|=2×100 max.

As described above, the magnetic flux φ1 interlinking the teeth withoutcoil winding (6 a, 16 a or 26 a) and the magnetic flux φ2 interlinkingthe teeth with coil winding (4 u, 4 v, 4 w, 14 u, 14 v, 14 w or 24 u, 24v, 24 w) are unbalanced, whereby the teeth with coil winding is morelikely to have magnetic saturation than the teeth without coil winding.

In the above embodiments 1 to 4, the teeth with coil winding (4 u, 4 v,4 w or 14 u, 14 v, 14 w) and the teeth without coil winding (6 a or 16a) have the same width. However, in the linear motor according to theembodiment 5, the teeth with coil winding (24 u, 24 v and 24 w) is widerthan the teeth without coil winding (26 a), whereby the magneticsaturation is relieved and the thrust characteristic is improved.

From the above description, the ratio of the maximum value |φ1max| ofmagnetic flux φ1 interlinking the teeth without coil winding to themaximum value |φ2max| of magnetic flux φ2 interlinking the teeth withcoil winding is 0.866, as obtained from the approximate expressions (1)and (2) that do not consider the magnetic flux of permanent magnets.Actually considering the magnetic flux of permanent magnets, the ratioof the width of the teeth without coil winding to the width of the teethwith coil winding is desirably from 0.5 to 0.9.

Also, by optimizing the ratio of the width of the teeth without coilwinding to the width of the teeth with coil winding as shown in FIG. 7,the thrust (FIG. 7C) of the linear motor having the structure as shownin FIG. 6 is greater than the thrust (FIG. 7A) of the linear motorhaving the structure as shown in FIG. 1, whereby the thrustcharacteristic is improved.

By the way, in the above description, the armatures 3 a, 3 b, 13 a, 13 band 23 a that singly compose the U phase, V phase and W phase areexemplified. However, a predetermined thrust is easily obtained byarranging the armature 3 a, 3 b, 13 a, 13 b and 23 a as plural armatureblocks in the thrust direction.

Also, in the above description, the moving coil type linear motor inwhich the field magnetic pole is the stator and the armature is theneedle is exemplified. However, the same effects are attained by amoving magnet type linear motor in which the field magnetic pole is theneedle and the armature is the stator.

INDUSTRIAL APPLICABILITY

As described above, the linear motor of the invention has the suppressedoccurrence of cogging thrust and the enhanced insulation of the motor bysimple methods, and is suitable for the uses for the actuator orconveying equipment for the table feeder of tooling machine.

1. A linear motor comprising: field magnetic poles having permanentmagnets arranged at an equal pitch; and an armature facing said fieldmagnetic poles and having an armature core; wherein the armature core isprovided with teeth arranged at an equal pitch and an armature coil withconcentrated winding around every other teeth; the number of magneticpoles with said permanent magnets and the number of teeth in saidarmature core are in a combination of 5n to 6n−1 (n: natural number);and the interval of teeth in said armature core is 5τ/6±τ/6 for themagnetic pole pitch τ.
 2. A linear motor comprising: field magneticpoles having permanent magnets arranged at an equal pitch; and anarmature facing said field magnetic poles and having an armature core;wherein, the armature core is provided with teeth arranged at an equalpitch and an armature coil with concentrated winding around every otherteeth; the number of magnetic poles with said permanent magnets and thenumber of teeth in said armature core are in a combination of 5n to 6n+1(n: natural number); and the interval of teeth in said armature core is5τ/6±τ/6 for the magnetic pole pitch τ.
 3. A linear motor comprising:field magnetic poles having permanent magnets arranged at an equalpitch; and an armature facing said field magnetic poles having anarmature core; wherein the armature core is provided with teeth arrangedat an equal pitch and an armature coil with concentrated winding aroundevery other teeth; the number of magnetic poles with said permanentmagnets and the number of teeth in said armature core are in acombination of 7n to 6n−1 (n: natural number); and the interval of teethin said armature core is 7τ/6±τ/6 for the magnetic pole pitch τ.
 4. Alinear motor comprising: field magnetic poles having permanent magnetsarranged at an equal pitch; and an armature facing said field magneticpoles and having an armature core; wherein the armature core is providedwith teeth arranged at an equal pitch and an armature coil withconcentrated winding around every other teeth; the number of magneticpoles with said permanent magnets and the number of teeth in saidarmature core are in a combination of 7n to 6n+1 (n: natural number);and the interval of teeth in said armature core is 7τ/6±τ/6 for themagnetic pole pitch τ.
 5. The linear motor according to claim 2, whereinthe teeth without armature coil winding located on both sides of saidarmature is different in the shape and pitch from the other teeth. 6.The linear motor according to claim 1, wherein in the teeth arranged atan equal pitch in said armature core, the teeth without armature coilwinding has a smaller width than the teeth with armature coil winding.7. The linear motor according to claim 4, wherein the teeth withoutarmature coil winding located on both sides of said armature isdifferent in the shape and pitch from the other teeth.
 8. The linearmotor according to claim 2, wherein in the teeth arranged at an equalpitch in said armature core, the teeth without armature coil winding hasa smaller width than the teeth with armature coil winding.
 9. The linearmotor according to claim 3, wherein the teeth arranged at an equal pitchin said armature core, the teeth without armature coil winding has asmaller width than the teeth with armature coil winding.
 10. The linearmotor according to claim 4, wherein the teeth arranged at an equal pitchin said armature core, the teeth without armature coil winding has asmaller width than the teeth with armature coil winding.
 11. The linearmotor according to claim 2, wherein the teeth without armature coilwinding located on both sides of said armature is different in the shapeand pitch from the other teeth; and the teeth without armature coilwinding has a smaller width than the teeth with armature coil winding.12. The linear motor according to claim 4, wherein the teeth withoutarmature coil winding located on both sides of said armature isdifferent in the shape and pitch from the other teeth; and the teethwithout armature coil winding has a smaller width than the teeth witharmature coil winding.